The Effect of Fiber Damage on the Longitudinal Creep of a Cfmmc

Fiber failures which may exist in a continuous fiber· composite before the .composite is loaded or generated while the composite is loaded, introduce an additional strain component not included in existing continuous fiber models. Equations are developed which can be used to calculate the magnitude of this additional strain. A Finite Element Model (FEM), in the form of a Representative Volume Element (RVE) , calculates the stress field surrounding a fiber break. Statistical analysis is used to infer the behavior of a large composite sample from the stress analysis of a single break. The creep strain, the time to failure, and time-dependent composite strength can all be calculated by combining the FEM results, the statistical analysis model, and knowledge of the initial average fiber length. Important variables included in the calculation are process-related parameters such as the fiber-matrix interface strength and roughness.